1 . Field of the Invention
The present invention relates to an apparatus to drive display devices and, more particularly, to a low power apparatus used with a display device, which cuts off unnecessary power to the display device in the event of abnormal inputs of horizontal and/or vertical synchronous signals.
2. Description of the Related Art
A schematic configuration of a conventional low power apparatus is shown in FIG. 1. Referring to FIG. 1, a low power apparatus typically comprises a control section 100, a first switching section 101, a second switching section 102, and a display section 103.
The control section 100 continuously checks horizontal and vertical signals H-SYNC and V-SYNC inputted thereto. If the control section 100 detects any abnormality in the input of horizontal and/or vertical synchronous signals, then the control section 100 enters a Display Power Management System (DPMS) mode. In such a DPMS mode, the control section 100 outputs a switching control signal to minimize power consumption by a display device.
The first switching section 101 switches voltage supplies to a first block stage (not shown) that is driven by voltage V1. Likewise, the second switching section 102 switches voltage supplies to a second block stage (not shown) that is driven by voltage V2. The switching control signals for the first and second switching sections 101 and 102 are provided from the control section 100. If the control section 100 detects that the input horizontal and vertical synchronous signals are normal, then the control section 100 provides first and second switching control signals to switch on the first and second switching sections 101 and 102, respectively, so that voltages V1 and V2 are supplied to the first and second block stages, respectively. On the other hand, if the control section 100 detects abnormality in the input horizontal and/or vertical synchronous signals, then the control section 100 recognizes that the display device is in a DPMS mode. In the DPMS mode, the control section 100 provides first and second switching control signals to switch off the first and second switching sections 101 and 102, respectively, so that the supplies of voltages V1 and V2 to the first and second block stages are cut off. The display section 103 typically includes light emitting diode displays that indicate to a user whether the control section 100 is in a normal mode or in a DPMS mode. For example, the display section 103 displays a green light in a normal mode and a blinking amber light in a DPMS mode. The operation of the display section 103 is controlled by the control section 100.
In a conventional configuration as described above, the control section 100 should be in operation all the time, because the control section 100 should continuously detect horizontal and vertical synchronous signals and check whether the display device is in a normal mode or in a DPMS mode. However, a significant amount of power, usually greater than 1 watt, is consumed for the operation of the control section 100 to check whether the display device is in a normal mode or in a DPMS mode, and there has been a limitation to reduce the power consumption to less than 1 watt. Further, since a plurality of switching devices is required to cut off power to multiple block stages, there has been a problem in terms of circuit integration and cost.